Sensation and Perception

Sensation: your window to the world

Perception: interpreting what comes in your window 

Transduction

-transforming signals into neural impulses 

-information goes from senses to the thalamus, the to the various areas in the brain

Sensory Adaptation

-decreased responsiveness to stimuli due to constant stimulation 

Cocktail-party Phenomenon

-the cocktail party effect describes the ability to focus ones listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations.

Energy vs. Chemical senses 

Energy senses: 

Chemical senses: 

Vision

-our most dominating sense

-visual capture

The longer the wave, the more red

The shorter the wavelength the more violent 

PHASE TWO

Phase four: In the brain

-goes to the Visual Cortex located in the Occipital Lobe of the Cerebral Cortex

-feature detectors 

-parallel processing

Trichromatic Theory

Three types of cones:

-Red

-blue

-green

These three types of cones can make millions of combinations of colors

-Does not explain afterimages or colorblindness well

 

Opponent Process Theory

-the sensory receptors come in pairs

'Red/gree

'Yellow/blue

'Black/white

-if the color is stimulated, the other is inhibited

 

Afterimages 

Hearing

Our auditory sense 

We hear sound waves

The height of the wave gives us the amplitude if the sound

-the frequency of the wave gives us the pitch if the sound

Transduction in the ear 

-sound waves hit the eardrum then advil then hammer then stirrup the oval window

-everything is just vibrating

-the COCHLEA is lined with mucus called basilar membrane there are hair cells

-when hair cells vibrate they turn vibrations into neural impulses which are called organ of Corti

-sent up to the thalamus up the auditory nerve

Place Theory

-different hairs vibrate in the cochlea when they different pitches

-so some hairs vibrate when they hear high and other vibrate when they hear low pitches 

 

Deafness

Conduction deafness

-something goes wrong with the sound and the vibration on the way to the cochlea

-you can replace the bones or get a hearing aid to help

Nerve (sensorineural deafness) 

-the hair cells in the cochlea get damaged

-loud noises can cause this type of deafness 

-noway to replace the hairs

-cochlea implant is possible

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Sensation

-bottom up processing

Analysis that begins with the sense receptors and works up to the brains integration of sensory information 

-top down processing 

Information processing guided by higher level mental process

As when we construct perceptions drawing on out experience and expectations 

Absolute Threshold

-the minimum stimulation needed to detect a stimulus 50% of the time 

Difference Threshold

-the minimum difference that a person can detect between two stimuli

-also known as just noticeable the 

Webers Law

-the idea that, to perceive a difference between two stimuli, they must differ by a constant percentage not a constant amount

Signal Detection Theory

-predicts how we detect a stimulus amid other stimuli

-assumes that we do not have an absolute threshold

-we detect stuff based on our experiences, motivations and fatigue level

Subliminal Stimulation

-below one's absolute threshold for conscious

Intensity

The amount of energy in a light wave determined by the height of the wave. The higher the wave the more intense the light is

Parallel Processing 

-the processing of several aspects of a problem simultaneously 

color, motion, form

Rods facilitate black and white vision

Cones facilitate color vision 

Frequency 

The number of complete wave lengths that pass throu point at a given time. This determines the pitch of a sound

Short waves= high frequency 

Long waves= low frequency 

Amplitude: is how loud the sound is. The higher the crest of the wave is the louder the sound is. It is measured in decibels

Sensory Interaction: the principle that one sense may influence another

Papillae

-those bumps on our tongue are called Papillae

-papillae help grip food while your teeth are chewing. They also have another special job-they contain your taste buds

-Sweet is sensed when our sensitive taste buds come into contact with sugar , it is found on the tip of your tongue  

-Salty is sensed when our salty taste buds come in contact with salt (sodium chloride)

-Sour is sensed when our sour taste buds come in contact with an acid 

-Bitter is sensed when our bitter taste buds come in contact with our alkaline chemical and it is based on 

-Spicy is sensed when the nocioreseptors in our mouth come into contact with a chemical that irritates them 

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Touch

-a receptors located in our skin

-gate control theory of pain

-the nervous system blocks or allows pain signals to pass to the brain 

Vestibular Sense

-tells us where our body is orientated in space

-our sense of balance

-located in our semicircular canals in our ears 

Kinesthetic Sense

-tells us where our body parts are

-receptors located in our muscles and joints 

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Perception 

-the process of organizing and interpreting information, enabling us to recognize meaningful objects and events

Visual Capture

-the tendency for vision to dominate the other senses

Gestalt Psychology 

-gestalt psychology emphasize our tendency to integrate pieces of information into meaningful wholes

Figure Ground Relationship 

-the organization of the visual felid into objects (figures) that stand out from their surroundings (ground)

Grouping

-the perceptual tendency to organize stimuli into groups that we understand 

-PROXIMITY 

we group near by figures together

-SIMILARITY

we group items that are similar together

-CONTINUITY

continuos patterns 

-CONNECTEDNESS

something uniformed and linked together

Depth Perception 

-the ability to see objects in three dimensions although the images that strike the retina are two dimensional

-allows us to judge distance 

 

How do we transfer twi dimensional  objects  to three-dimensional peeception?

-binoculars Cues: depth cues that depend on two eyes 

-monocu

Binocular Cues

-Retinal Disparity: a binocular cue fir seeing depth 

The closer an object comes to you the greater the disparity is between to the two images 

 

Monocular Cues

-interposition: if something is blocking our view we perceive it as closer 

-relative Size: if we know that two objects are similar in size, the one that looks smaller us farther away

-relative Clarity:we assume hazy objects are farther away

-texture gradient:the coarser it looks the closer it is 

-relative height: things higher in our field of vision they look farther away

-relative motion:things that are closer appear to move more quickly 

-liner perspective:parallel lines seem to converge wit distance 

-light snd shadow: dimmer object appear farther away because they reflect less light

Phi Phenomenon 

-an illusion of movement created when two or mire adjacent lights blink on and off in succession 

Perceptual Consistency

-perceiving objects as unchanging even as illumination and retinal images change

Brain Structures and their Functions

The nervous system is your body's decision and communication center. The central nervous system (CNS) is made of the brain and the spinal cord and the peripheral nervous system (PNS) is made of nerves. Together they control every part of your daily life, from breathing and blinking to helping you memorize facts for a test. Nerves reach from your brain to your face, ears, eyes, nose, and spinal cord... and from the spinal cord to the rest of your body. Sensory nerves gather information from the environment, send that info to the spinal cord, which then speed the message to the brain. The brain then makes sense of that message and fires off a response. Motor neurons deliver the instructions from the brain to the rest of your body. The spinal cord, made of a bundle of nerves running up and down the spine, is similar to a superhighway, speeding messages to and from the brain at every second.

The brain is made of three main parts: the forebrain, midbrain, and hindbrain. The forebrain consists of the cerebrum, thalamus, and hypothalamus (part of the limbic system). The midbrain consists of the tectum and tegmentum. The hindbrain is made of the cerebellum, pons and medulla. Often the midbrain, pons, and medulla are referred to together as the brainstem.

The Cerebrum: The cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes": the frontal lobe, parietal lobe, occipital lobe, and temporal lobe.

• Frontal Lobe- associated with reasoning, planning, parts of speech, movement, emotions, and problem solving
• Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual processingTemporal Lobe- associated with perception and recognition of auditory stimuli, memory, and speech

Note that the cerebral cortex is highly wrinkled. Essentially this makes the brain more efficient, because it can increase the surface area of the brain and the amount of neurons within it. We will discuss the relevance of the degree of cortical folding (or gyrencephalization) later. (Go here for more information about cortical folding)

A deep furrow divides the cerebrum into two halves, known as the left and right hemispheres. The two hemispheres look mostly symmetrical yet it has been shown that each side functions slightly different than the other. Sometimes the right hemisphere is associated with creativity and the left hemispheres is associated with logic abilities. The corpus callosum is a bundle of axons which connects these two hemispheres.

Nerve cells make up the gray surface of the cerebrum which is a little thicker than your thumb. White nerve fibers underneath carry signals between the nerve cells and other parts of the brain and body.

The neocortex occupies the bulk of the cerebrum. This is a six-layered structure of the cerebral cortex which is only found in mammals. It is thought that the neocortex is a recently evolved structure, and is associated with "higher" information processing by more fully evolved animals (such as humans, primates, dolphins, etc). For more information about the neocortex, click here.

The Cerebellum: The cerebellum, or "little brain", is similar to the cerebrum in that it has two hemispheres and has a highly folded surface or cortex. This structure is associated with regulation and coordination of movement, posture, and balance.

The cerebellum is assumed to be much older than the cerebrum, evolutionarily. What do I mean by this? In other words, animals which scientists assume to have evolved prior to humans, for example reptiles, do have developed cerebellums. However, reptiles do not have neocortex. Go here for more discussion of the neocortex or go to the following web site for a more detailed look at evolution of brain structures and intelligence: "Ask the Experts": Evolution and Intelligence

Limbic System: The limbic system, often referred to as the "emotional brain", is found buried within the cerebrum. Like the cerebellum, evolutionarily the structure is rather old.

This system contains the thalamus, hypothalamus, amygdala, and hippocampus.

Brain Stem: Underneath the limbic system is the brain stem. This structure is responsible for basic vital life functions such as breathing, heartbeat, and blood pressure. Scientists say that this is the "simplest" part of human brains because animals' entire brains, such as reptiles (who appear early on the evolutionary scale) resemble our brain stem. Look at a good example of this here.

The brain stem is made of the midbrain, pons, and medulla.